It is generally considered by the layman that four kinds of poisonous snakes are found in the United States—the rattlesnake, cottonmouth, copperhead and coral snake. This grouping, although somewhat arbitrary and certainly not zoologically correct, is firmly established in the minds of most people and may very well be here to stay. Nevertheless, a more accurate and scientific approach is possible if we consider each species and subspecies as a different kind. Illustrations in this booklet show the 16 kinds (species and subspecies) of poisonous snakes known in Texas. These photographs, together with descriptions in the text, should aid in identification. The accompanying distribution map for each form has been compiled from county records based on museum specimens, but in a few cases reliable “sight” records have been used as proof of a snake’s occurrence within a county. Distribution of snakes within Texas is incompletely known because of a lack of reliable records; for this reason, the distribution maps are necessarily far from complete. It is hoped, however, that the lists will be brought up to date as new localities come to light. If the reader can make any additions to the present lists, he is asked to communicate with the author or to deliver specimens to the nearest large college, zoo or museum maintaining a zoological collection. Only 16 of the approximately 106 different kinds of snakes found in the state are dangerously poisonous to man, and some are so rare that they are seldom seen. In addition, we have in Texas several species of smaller snakes known as opisthoglyphs, each possessing a mild venom and a set of small grooved fangs far back in the upper jaw. Because of their weak and limited supply of venom and small fangs, which are poorly adapted for injecting poison into large animals, these rear-fanged snakes are considered harmless to man. By far, the majority of species are small, being not more than 15 inches long and about three-sixteenths of an inch thick. In this group are the blackheaded snakes (genus _Tantilla_) found over most of the state. The slightly larger spotted night snakes (genus _Hypsiglena_) of west and central Texas have enlarged but ungrooved teeth in the upper jaw. Two Mexican rear-fanged snakes, found as far north as the Brownsville region, are somewhat larger. They are the blackstriped snake (_Coniophanes imperialis imperialis_) which grows to about 20 inches in length, and the Texas cat-eye snake (_Leptodeira annulata septentrionalis_), which reaches a length of about three feet. Still another species, the very rare Texas lyre snake (_Trimorphodon vilkinsonii_), is known from extreme western Texas. It is generally less than three feet long.